Biomedical subjects

A Amery

Publications and source records attributed to A Amery.

At least 91 records · Page 5Linked to original sources

PubMed1992

Determinants of serum zinc in a random population sample of four Belgian towns with different degrees of environmental exposure to cadmium.

This report investigated the distribution of serum zinc and the factors determining serum zinc concentration in a large random population sample. The 1977 participants (959 men and 1018 women), 20-80 years old, constituted a stratified random sample of the population of four Belgian districts, representing two areas with low and two with high environmental exposure to cadmium. For each exposure level, a rural and an urban area were selected. The serum concentration of zinc, frequently used as an index for zinc status in human subjects, was higher in men (13.1 mumole/L, range 6.5-23.0 mumole/L) than in women (12.6 mumole/L, range 6.3-23.2 mumole/L). In men, 20% of the variance of serum zinc was explained by age (linear and squared term, R = 0.29), diurnal variation (r = 0.29), and total cholesterol (r = 0.16). After adjustment for these covariates, a negative relationship was observed between serum zinc and both blood (r = -0.10) and urinary cadmium (r = -0.14). In women, 11% of the variance could be explained by age (linear and squared term, R = 0.15), diurnal variation in serum zinc (r = 0.27), creatinine clearance (r = -0.11), log gamma-glutamyltranspeptidase (r = 0.08), cholesterol (r = 0.07), contraceptive pill intake (r = -0.07), and log serum ferritin (r = 0.06). Before and after adjustment for significant covariates, serum zinc was, on average, lowest in the two districts where the body burden of cadmium, as assessed by urinary cadmium excretion, was highest. These results were not altered when subjects exposed to heavy metals at work were excluded from analysis.

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PubMed1992

Factors influencing the cadmium body burden in a population study.

The cadmium body burden, as estimated from 24-h urinary cadmium (Cd-U), was determined in 1523 non-occupationally exposed subjects living in five areas of Belgium. It increased with age until 55-65 years in both sexes and thereafter decreased slightly. It was higher in smokers but was inversely associated with alcohol consumption and social class. In men only, it was also positively correlated with body mass index. After the menopause, women showed a significant increase in 24-h Cd-U independently of the other factors. In addition, the cadmium body burden was independently associated with place of residence in both sexes. Highest levels of Cd-U were found in subjects living in an area with soils heavily polluted by cadmium.

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PubMed1992

Ambulatory blood pressure monitoring in elderly patients with isolated systolic hypertension.

OBJECTIVES: This study compared clinic and ambulatory blood pressure measurement and the reproducibility of these measurements in older patients with isolated systolic hypertension (ISH). PATIENTS: Eighty-seven patients aged greater than or equal to 60 years with ISH on clinic measurement were followed in the placebo run-in phase of the Syst-Eur trial. METHODS: Clinic blood pressure was defined as the mean of two blood pressure readings on each of three clinic visits (six readings in total). Ambulatory blood pressure was measured over 24 h using non-invasive ambulatory blood pressure monitors. RESULTS: Daytime ambulatory systolic pressure was, on average, 21 mmHg lower than the clinic blood pressure, whereas diastolic pressure was, on average, similar with both techniques of measurement. In the 42 patients who had repeat measurements, clinic blood pressure levels nad the amplitude of the diurnal blood pressure profile (fitted by Fourier analysis) were equally reproducible. However, both were less reproducible than ambulatory blood pressure levels. The repeatability coefficients, expressed as per cent of near maximum variation (four times the standard deviation of a given measurement), were 52% and 45% for the clinic systolic and diastolic pressures, 56% and 42% for the amplitude of the diurnal profile, and 29% and 26% for mean 24-h pressures. CONCLUSIONS: In older patients with ISH, clinic and ambulatory systolic blood pressure measurements may differ largely: the prognostic significance of this difference remains to be elucidated. Furthermore, in these patients the level of pressure is more reproducible by daytime ambulatory blood pressure measurement than by clinic measurement.

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PubMed1992

[Isolated systolic hypertension in persons older than 60].

Isolated systolic hypertension (ISH) is generally defined as a systolic pressure of 160 mmHg or more, with a diastolic pressure cut-off point below 95 mmHg in some studies and 90 mmHg in others. Its prevalence and incidence vary from 3 to 30% depending on the definition applied, methodology of measurement, as well as the population and the age and sex of the patients. Mechanisms that could lead to the development of isolated systolic hypertension are discussed, especially the role of atherosclerosis and sodium intake. Comparing results from different countries, the Intersalt study showed that the age related rise in systolic pressure was positively related to the mean sodium excretion in that country. A post-hoc analysis of data from 4 Belgian groups could not show such a correlation within our country. The risks of systolic hypertension on mortality and morbidity in the elderly are considered. The need for further studies to quantify the risk and to establish the effect of treatment is emphasized. Three such studies in patients above the age of 60 years with ISH were started. The studies are double-blind, placebo-controlled trials and the main purpose is to examine the influence of treatment on morbidity, mortality, and general well-being. In the American SHEP study the patients of the actively treated group received a diuretic and possibly a beta-blocker or reserpine. The results indicate a significant reduction in non fatal stroke, heart failure and myocardial infarction without a significant reduction in fatal stroke, fatal myocardial infarction, cardiovascular or all cause mortality. Studies in other continents are still in progress, such as the Syst-Chin in China and the Syst-Eur trial in Europe. They may indicate whether the results obtained in the U.S.A. can be extrapolated to other continents and whether the use of other drugs without metabolic disturbances, such as calcium entry blockers and angiotensin converting enzyme inhibitors, produce a similar reduction in events. Additional studies are needed to establish the effect of reducing salt intake in younger age groups on the prevalence of ISH and of the related morbidity and mortality.

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PubMed1992

[SYST-EUR: a multicenter trial of treatment of systolic hypertension in aged subjects. An initial report].

Syst-Eur is a multicentre placebo-controlled outcome trial, designed by the European Working Party on High Blood Pressure in the Elderly (EWPHE), to investigate the effect of antihypertensive treatment on the incidence of stroke in elderly patients with isolated systolic hypertension (ISH). Eligible patients must be at least 60 years old and have a systolic blood pressure averaging 160-219 mmHg with a diastolic blood pressure less than 95 mmHg. The present paper in an interim report on the first 316 patients randomized into this trial. The placebo (N = 170) and active treatment (N = 146) groups were similar at randomization with respect to age (73 +/- 8 years; mean +/- standard deviation), sitting blood pressure (178 +/- 12/85 +/- 7 mmHg), percentage men (34%) and percentage of patients with cardiovascular complications (29%). After randomization blood pressure fell more (p < 0.001) on active treatment than in the placebo group (19 +/- 20/6 +/- 10 mmHg versus 7 +/- 19/1 +/- 10 mmHg for the sitting blood pressure). This first interim report on the Syst-Eur trial demonstrates that a multinational trial in elderly patients with ISH is feasible and that a significant blood pressure difference between the 2 treatment groups can be achieved and maintained. New centres are being recruited in order to randomize a total of 3,000 patients.

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PubMed1992

Trials in elderly patients with isolated systolic hypertension.

The hypothesis that antihypertensive drugs should be prescribed to elderly patients with isolated systolic hypertension is being addressed in at least 3 trials: the Systolic Hypertension in the Elderly Program (SHEP) in the United States, a trial in China, and the Syst-Eur study in Europe. The SHEP trial has recently reported its final morbidity and mortality results. This article summarizes the protocol of the European study. To be eligible for the Syst-Eur trial, patients must be at least 60 years old and have a systolic blood pressure averaging 160-219 mmHg with a diastolic pressure less than 95 mmHg. Patients must give their informed consent and be free of major cardiovascular and non-cardiovascular diseases at entry. The patients are randomized into active treatment or placebo. Active treatment consists of nitrendipine (10-40 mg/d), combined with enalapril (5-20 mg/d) and hydrochlorothiazide (12.5-25 mg/d), as necessary. The control group received matching placebos. The drugs (or matching placebos) are stepwise titrated and combined in order to reduce systolic blood pressure by 20 mmHg at least to a level below 150 mmHg. Morbidity and mortality are monitored to enable an intention-to-treat and per protocol comparison of the outcome in the two treatment groups.

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PubMed1992

Mean and range of the ambulatory pressure in normotensive subjects.

To perform a meta-analysis of published reports in an attempt to determine the mean and range of normal ambulatory blood pressure (BP), 23 studies including a total of 3,476 normal subjects were reviewed. Most studies were compatible with a mean 24-h BP in the range of 115-120/70-75 mmHg, a mean day time BP of 120-125/75-80 mmHg, and a mean night time BP of 105 to 110/60 to 65 mmHg. With weighting for the number of subjects included in the individual studies, the 24-h BP averaged 118/72 mmHg, the day time BP 123/76 mmHg, and the night time BP 106/64 mmHg. The night/day pressure ratio averaged 0.87 for systolic and 0.83 for diastolic BP, with ranges across the individual studies from 0.79 to 0.92 and from 0.75 to 0.90, respectively. If the mean +/- 2 standard deviation interval in the various studies was considered normal, the range of normality was on average 97 to 139/57 to 87 mmHg for the 24-h BP, 101 to 146/61 to 91 mmHg for the day time BP, and 86 to 127/48 to 79 mmHg for the night time BP. Until the results of prospective studies on the relation between the ambulatory BP and the incidence of cardiovascular morbidity and mortality become available, the aforementioned intervals, which summarize the experience of 23 investigators, could serve as a temporary reference for clinical practice.

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PubMed1991

Blood pressure, the prevalence of cardiovascular diseases, and exposure to cadmium: a population study.

In a population study conducted from 1985 to 1989 in Belgium, the authors investigated whether exposure to cadmium is associated with blood pressure elevation and with an increased prevalence of cardiovascular diseases. The participants, aged 20-88 years, constituted a random sample of the households living in two low exposure areas (n = 803) and two high exposure areas (n = 1,283). For each exposure level, a rural and an urban district were selected. The cadmium levels in blood (8.5 vs. 11.0 nmol/liter) and urine (7.2 vs. 8.7 nmol/24 hours) were significantly (p less than 0.001) raised in the two high exposure areas compared with the two low exposure areas (p less than 0.001). Systolic pressure was similar in both rural areas, but in the urban area with high exposure systolic pressure was 5 mmHg (p less than 0.001) higher than in the control town. Diastolic pressure was similar in the four districts and the same was true for the prevalence of hypertension and of other cardiovascular diseases. Adjustment of systolic pressure for blood and urinary cadmium did not remove the difference in systolic pressure between both urban areas, suggesting that it was not related to the cadmium burden on the environment. Further analyses in individual subjects showed that neither blood pressure nor the presence of cardiovascular diseases were significantly and positively correlated with blood and urinary cadmium. Thus, the present population study did not confirm the hypothesis that increased exposure of the population to cadmium is associated with blood pressure elevation and with a higher prevalence of cardiovascular diseases.

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PubMed1991

Review of the major hypertension trials in the elderly.

The different intervention trials in elderly hypertensives are compatible with the hypothesis that hypotensive drug treatment can decrease cardiovascular mortality mainly by decreasing cerebrovascular mortality. A decrease in the fatal and nonfatal cardiovascular event rate is mainly due to a decrease in cerebrovascular events. It is not established whether hypotensive drug treatment is advisable in symptomless patients with isolated systolic hypertension and in patients with uncomplicated hypertension above age 80. A sudden reduction in blood pressure should be avoided, but whether a progressive reduction of systolic blood pressure below 140 mmHg and of diastolic blood pressure below 85 mmHg is dangerous or advantageous remains to be established.

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PubMed1991

Hormonal effects of the diuretic xipamide in healthy men.

The effect of xipamide on plasma alpha-atrial natriuretic peptide and the renin-aldosterone-kallikrein system have been studied in 12 healthy men, using a double-blind cross-over design. After a run-in period on placebo of 1 week, the subjects were treated with either placebo (n = 6) or xipamide 20 mg once daily (n = 6) for 16 weeks and were then switched to the alternative medication for another 16 weeks. The plasma concentration of alpha-atrial natriuretic peptide fell after 1 week of xipamide administration and increased during prolonged xipamide administration but remained reduced. The changes in plasma alpha-ANP observed after 1 week of xipamide were negatively correlated with the changes in hematocrit and hemoglobin. Plasma renin activity (PRA), aldosterone concentration (PAC), and urinary excretion of aldosterone and kallikrein increased after 1 week of xipamide administration, levelled off during the second and fourth weeks, but remained elevated during further prolonged xipamide administration for 16 weeks. The xipamide-induced changes in PRA and PAC were positively correlated with the changes in the hematocrit and hemoglobin. The changes in plasma renin, aldosterone, and alpha-atrial natriuretic peptide during xipamide administration may be related to diuretic-induced volume contraction.

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PubMed1991

Syst-Eur. A multicentre trial on the treatment of isolated systolic hypertension in the elderly: objectives, protocol, and organization.

The Syst-Eur Trial is a concerted action of the European Community's Medical and Health Research Programme. The trial is carried out in consultation with the World Health Organization, the International Society of Hypertension, the European Society of Hypertension and the World Hypertension League. This article describes the objectives and the protocol of Syst-Eur, a multicentre trial designed by the European Working Party on High Blood Pressure in the Elderly (EWPHE), to test the hypothesis that antihypertensive treatment of elderly patients with isolated systolic hypertension results in a significant change in stroke morbidity and mortality. Secondary endpoints include cardiovascular events, such as myocardial infarction and congestive heart failure. To be eligible patients must be at least 60 years old and have a systolic blood pressure averaging 160-219 mmHg with a diastolic pressure less than 95 mmHg. Patients must give their informed consent and be free of major cardiovascular and non-cardiovascular diseases at entry. The patients are randomized to active treatment or placebo. Active treatment consists of nitrendipine (10-40 mg/day), combined with enalapril (5-20 mg/day) and hydrochlorothiazide (12.5-25 mg/day), as necessary. The patients of the control group receive matching placebos. The drugs (or matching placebos) are stepwise titrated and combined in order to reduce systolic blood pressure by 20 mmHg at least to a level below 150 mmHg. Morbidity and mortality are monitored to enable an intention-to-treat and per-protocol comparison of the outcome in the 2 treatment groups. A one-year pilot trial (1989) showed that the protocol is practicable. The Ethics Committee therefore decided to start the definite study (1990), in which randomized patients will be followed for 5 years. Recruitment of new centres and of the required 3,000 patients will last 3 years (until 1993).

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PubMed1991

Is prevention of vascular dementia possible? The Syst-Eur Vascular Dementia Project.

Vascular dementia (VD) is the second most common cause of dementia in the elderly after Alzheimer's disease (AD). Prevalence estimates from community surveys indicate that, on average, 5% of persons over 65 and 15 to 20% of people over 80 suffer from "severe dementia". Clinico-pathological studies have shown that AD accounts for 50 to 60% of the cases and VD for about 10 to 20%; 20% of the patients have both disorders. The incidence rate of VD ranges from 7 per 1,000 person-years in normal volunteers to 16 per 1,000 person-years in subjects with risk factors for strokes, particularly high blood pressure. The only effective therapeutic approach to VD is the prevention of strokes, mainly through the treatment of hypertension; however, none of the therapeutic trials has included VD prevention as one of its treatment goals. Syst-Eur Study is a European placebo controlled trial which aims to determine whether morbidity and mortality are changed when elderly patients (60 years and over) with isolated systolic hypertension are treated. In this trial, the incidence of VD will be carefully recorded during the five year follow-up of the expected 3,000 patients. The present side project to the Syst-Eur trial will specifically address the following questions: does antihypertensive treatment reduce the incidence of VD?, and how do the cognitive functions of elderly patients change when treated with active or placebo treatment? The protocol is based on the administration of the MMS (Folstein) once a year to all patients. If the MMS score is 23 or less, a set of criteria will be used to establish the diagnosis of vascular dementia. A pilot study has demonstrated the feasibility of the trial. The main study is in progress.

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PubMed1991

The inheritance of left ventricular structure and function assessed by imaging and Doppler echocardiography.

The heritability of left ventricular structure and function was studied in 53 pairs of monozygotic and dizygotic twins, aged 18 to 31 years, by means of M-mode and Doppler echocardiography. A significant fraction of the phenotypic variances of left ventricular wall thickness was explained by genetic variance. For the left ventricular internal dimension, however, no genetic effect was found after correction for body weight. After appropriate adjustment a genetic component of 32% was found for aortic peak flow velocity, 55% for stroke distance, and 47% for minute distance. The early and late diastolic peak flow velocities at the mitral valve showed a genetic component estimated at 43% and 26%, respectively. The inheritance of the late/early diastolic peak flow velocity ratio was estimated at 53%. In conclusion, these data suggest a significant genetic component for left ventricular structural features but not for cavity dimension. A significant influence of heredity was detected for left ventricular inflow and outflow characteristics.

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PubMed1991

Isolated systolic hypertension in the elderly: an epidemiologic review.

Isolated systolic hypertension (ISH) is usually defined as a systolic blood pressure greater than or equal to 160 mm Hg and diastolic blood pressure less than 90 or 95 mm Hg. Systolic blood pressure has been found to increase with age in most populations studied and thus the prevalence of ISH can be expected to increase with age. ISH is more prevalent in elderly women than in elderly men. Estimates of the prevalence of ISH vary according to its definition and the number of blood pressure measurements. There is evidence that the prevalence of ISH is decreasing. Results of a survey of the prevalence of ISH in 11 countries are presented; the estimates among men aged 60 to 69 years ranged from 1% in Israel to 24% in Norway. Only a prospective standardized survey conducted in several countries will reveal the true prevalence of ISH.

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PubMed1991

Does environmental exposure to cadmium represent a health risk? Conclusions from the Cadmibel study.

Cadmium is a very dispersive pollutant which has progressively accumulated in the environment mainly in the areas where nonferrous smelters have been in operation. An important toxicological feature of cadmium is its exceptionally long biological half-life in the human body. For the general population mainly exposed to cadmium by the diet and smoking, the kidney is the main target organ. Some studies have also suggested that cadmium might play a role in the pathogenesis of hypertension. A cross-sectional study (called Cadmibel) was undertaken to assess whether environmental pollution by cadmium in Belgium might represent a health risk. This paper does not present the detailed results of this study which are published elsewhere but simply report its main conclusions. A total number of 2327 subjects (stratified according to age and sex) was randomly sampled in two urban (Liège and Charleroi) and two rural (Hechtel-Eksel and Noorderkempen) areas, with different environmental pollution by cadmium. After allowing for the various factors known to influence cadmium accumulation, it was estimated that the cadmium body burden of the residents of the most polluted district (Noorderkempen) was 50 to 85% higher than in the less polluted areas. No statistical association was found between environmental exposure to cadmium and blood pressure elevation or the prevalence of cardiovascular diseases. However, the study has shown that the environmental exposure of the general population to cadmium may induce slight renal tubular dysfunction and may probably also affect cadmium homeostasis. The probability of tubular dysfunction (as assessed by sensitive tests) is about 10% when cadmium in urine reaches 2 micrograms/day. The morbidity associated with the changes in the renal proximal tubule and the calcium metabolism observed when the body burden of cadmium exceeds this value remains to be assessed.

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PubMed1991

Pulse rate and sodium intake interact to determine blood pressure. A population study.

It has been suggested that certain factors need to be present for the pressor effect of sodium to become apparent. The present population study investigated whether pulse rate (PR) and salt intake interact to determine blood pressure (BP). Twenty-four hour urinary sodium (UNaV) was used as a measure of salt intake. A random population sample, including 2081 subjects with a minimum age of 18 years, was stratified on tertiles of PR. In subjects with a slow PR(less than 68 beats/min) and in those with a fast PR (greater than 78 beats/min), a significant curvilinear relationship between BP and UNaV was found, while in subjects with an intermediate PR the BP-UNaV correlation was not significant. There was also a significant interaction between PR and UNaV, indicating that when UNaV increased from 160 to 300 mmol/24 h, systolic/diastolic BP rose by 2/1 mm Hg in the fast PR third, but declined by 1/1 mm Hg in the slow PR third. These divergent trends could not be explained by smoking habits or alcohol consumption and were still present after cumulative adjustment for other important correlates of BP, ie, gender, age, body weight, urinary potassium, and contraceptive pill intake in women. In conclusion, the present data suggest that in subjects with a pulse rate greater than 78 beats/min a high salt intake may be associated with blood pressure elevation, whereas the opposite tendency is observed in individuals with a pulse rate less than 68 beats/min.

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PubMed1991

Risks and benefits in the trial of the European Working Party on High Blood Pressure in the Elderly.

Hypertensive patients over the age of 60 years were admitted to a double-blind placebo-controlled trial. Patients in the actively treated group received a combined potassium-losing and -sparing diuretic (triamterene 50 mg plus hydrochlorothiazide 25 mg; n = 416); this dose could be doubled and methyldopa (up to 2 g, daily) was added in 35% of patients when blood pressure remained high. The placebo group (n = 424) received matching capsules and tablets. Adverse effects were assessed in the double-blind period of the trial by calculating the incidence of abnormal biochemical results, investigator reports of diseases and prescriptions of concomitant therapy and a self-administered symptom questionnaire completed by patients. In 1000 hypertensive subjects over 60 years of age, 1 year of active treatment would prevent 11 fatal cardiac events, 6 fatal and 11 non-fatal strokes and 8 cases of severe congestive heart failure. No unexpected adverse treatment effects were observed. A significant excess incidence rate (per 1000 person years) was found in the active group compared with placebo for: (1) impaired renal function, a serum creatinine greater than 180 mumol/l (2.0 mg/dl); (2) mild hypokalaemia, a serum potassium less than 3.5 mmol/l; (3) reports of gout; and (4) an elevated serum uric acid greater than 0.52 mmol/l in men or greater than 0.46 in women. Elevated blood sugar and prescriptions for hypoglycaemic drugs tended to be more frequent in the actively treated group, but this difference was not statistically significant. In both groups, there was a low incidence (less than 7 per 1000 person years) of anaemia and depression and diseases of the liver, gall bladder or pancreas.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1991

Effect of antihypertensive medication on endurance exercise capacity in hypertensive sportsmen.

Beta-adrenoceptor blockade can influence exercise capacity negatively, but data on the effect of converting enzyme inhibition and of calcium entry blockade on exercise capacity in hypertensive sportsmen are scarce. This report deals with the effect of the various types of antihypertensive medication on endurance exercise capacity in 14 hypertensive sportsmen, aged 39 +/- 3 years and weighing 73 +/- 2 kg (mean +/- s.e.m.). The patients were treated for 3 weeks with either placebo, atenolol (50 mg/day) enalapril (10 mg/day) or verapamil (240 mg/day) following a double-blind randomized cross-over design. At the end of each treatment period, they performed an endurance exercise test on the bicycle until exhaustion at 70% of their previously determined exercise capacity. Venous blood was sampled before and after exercise. In comparison with placebo, total exercise duration was not affected by enalapril (-3 +/- 7%) or verapamil (-7 +/- 11%). During treatment with atenolol, two patients had to interrupt their intake of the beta-blocker because of side effects. In the 12 remaining subjects, exercise duration was significantly decreased by 38 +/- 12% (P less than 0.01). Atenolol also induced decreases in plasma-free fatty acid concentration before and after exercise and an increase in potassium concentration after exercise, whereas enalapril and verapamil did not induce metabolic changes. During exercise, systolic blood pressure was decreased by atenolol (P less than 0.001) and enalapril (P less than 0.01) and diastolic blood pressure by enalapril (P less than 0.001), verapamil (P less than 0.05) and atenolol(P = 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)

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